1. Field of the Invention
The present invention relates to an oil control valve for supplying hydraulic oil to a blade oil hydraulic actuator for controlling an intake valve or exhaust valve to open or close timely depending on the operating condition of an engine so as to control the oil level of the oil hydraulic actuator.
2. Description of the Related Art
FIG. 1 is a sectional diagram showing a blade oil hydraulic actuator according to the related art. Reference numeral 1 indicates an intake cam shaft (hereinafter, simply referred to as a cam shaft) provided with an intake cam 1a. Numeral 2 indicates a timing pulley provided at an end of the cam shaft 1. Numeral 3 indicates an actuator coupled to the cam shaft 1 so as to control valve opening/closing timing. Hydraulic oil supplied to drive the actuator 3 is lubricating oil for the engine (not shown). The actuator 3 is driven by the hydraulic oil to vary a displacement angle of the cam shaft 1 so that the opening and closing timing of the intake valve (not shown) is continuously controlled. Numeral 4 indicates a bearing of the cam shaft 1. Numeral 5 indicates a housing of the actuator 3 and is rotatably fitted to the cam shaft 1.
Numeral 6 indicates a case secured to the housing 5. Numeral 7 indicates a blade rotor connected to the cam shaft 1 by a bolt 8 and housed in the case 6. The rotor 7 is rotatable with respect to the case 6. Numeral 9 indicates a tip seal provided between the case 6 and the rotor 7 so as to prevent leakage of oil between oil hydraulic chambers bounded by the case 6 and the rotor 7. Numeral 10 indicates a back spring formed of a flat spring for forcing the tip seal 9 to be in contact with the rotor 7. Numeral 11 indicates a cover secured to the case 6. Numeral 12 indicates a bolt securing the housing 5, the case 6 and the cover 11 to each other. Numeral 13 indicates an O-ring. Numeral 14 indicates a plate. Numeral 15 indicates a bolt securing the plate 14 to the cover 11. Numerals 16 and 17 indicate O-rings. Numeral 18 indicates a cylindrical holder provided in the rotor 7. An engagement hole 18a, for engaging a plunger described later therewith is provided in the holder 18 to extend in an axial direction.
Numeral 19 indicates a plunger slidably provided in the housing 5 and provided with an engagement shaft portion 19a fitted within the hole 18a of the holder 18. Numeral 20 indicates a spring for urging the plunger 19 toward the holder 18. Numeral 21 indicates a plunger oil passage for introducing the hydraulic oil into the engagement hole 18a of the holder 18. The hydraulic oil introduced into the engagement hole 18a of the holder 18 via the plunger oil passage 21 displaces the plunger 19 against the urging force of the spring 20 so that the holder 18 is released from the locking action provided by the plunger 19. Numeral 22 indicates an air vent. Numeral 22 indicates an air vent. Numeral 23 indicates a shaft bolt for securing the rotor 7 to the cam shaft 1. Numeral 24 indicates an air vent.
Numeral 25 indicates a first oil passage provided in the cam shaft 1 and the rotor 7 to communicate with a lag oil hydraulic chamber (not shown) for displacing the rotor 7 in a lagging direction. Numeral 26 indicates a second oil passage provided in the cam shaft 11 and the rotor 7 to communicate with an advance oil hydraulic chamber (not shown) for displacing the rotor 7 in an advancing direction.
Numeral 27 indicates a oil control valve (hereinafter, referred to as OCV) for supplying hydraulic oil to the actuator 3 and controlling the quantity of the oil supplied. Numeral 28 indicates a substantially cylindrical valve housing having a port corresponding to an open end of pipelines 32-35 described later. Numeral 29 indicates a spool that slides in the valve housing 28 in an axial direction of the valve housing 28. Numeral 30 indicates a spring that urges the spool in one direction. Numeral 31 indicates a linear solenoid for actuating the spool 29 against the urging force of the spring 30. Numeral 32 indicates a supply pipeline for guiding the hydraulic oil supplied via an oil pump described later to the valve housing 28. Numeral 33 indicates a drain pipeline for returning the hydraulic oil inside the valve housing 28 to an oil pan described later. Numeral 34 indicates a first pipeline for guiding the hydraulic oil to the first oil passage 25. Numeral 35 indicates a second pipeline for guiding the hydraulic oil to the second oil passage 26. Numeral 36 indicates an oil pan. Numeral 37 indicates an oil pump. Numeral 38 indicates an oil filter for eliminating impurities from the hydraulic oil. The oil pan 36, the oil pump 37 and the oil filter 38 constitute a lubricating system for lubricating various parts o the engine (not shown). The oil pan 36, the oil pump 37, the oil filter 38 and the OCV 27 constitute a system for supplying the hydraulic oil to the actuator 3.
Numeral 39 indicates an engine block provided with a recess for accommodating the valve housing 28. The interior of the recess of the engine block 39 houses the pipelines 32-35 so as to allow open ends of the pipelines 32-35 to face respective ports of the valve housing 28.
Numeral 40 indicates an electronic control unit (ECU). The ECU controls fuel injection quantity, ignition timing and valve opening/closing timing by actuating an injector, ignitor and the OCV 27 based on signals from an intake air quantity sensor (not shown), a throttle sensor (not shown), a water temperature sensor (not shown), a crank angle sensor (not shown) and a cam angle sensor (not shown). The ECU also controls the OCV 27 closing timing subsequent to turning off of the ignition switch.
A description will now be given of the operation of the actuator 3 and the OCV 27.
When the engine is at a stop, the rotor 7 is at a position with a maximum lagging displacement. That is, the rotor 7 is rotated by a maximum advance angle with respect to the housing 5. The oil pump 37 is not in operation so that the hydraulic oil is not supplied to the first oil passage 25, the second oil passage 26 and the plunger oil passage 21. The pressure of the oil retained inside the actuator 3 is relatively low. Therefore, the plunger 19 is thrust against the holder 18 by the urging force of the spring 20. The engagement shaft portion 19a of the plunger 19 is engaged with the engagement hole 18a of the holder 18 so that the housing 5 and the rotor 7 remains locked to each other.
When the engine is started in this locked state, the oil pump 37 is put into operation so that the pressure of the hydraulic oil supplied to the OCV 27 is increased. The hydraulic oil is supplied by the OCV 27 to the lag oil hydraulic chamber (not shown) in the actuator 3 via the first pipeline 34 and the first oil passage 25. Due to the pressure built up in the lag oil hydraulic chamber, a slide plate (not shown) is displaced toward the advance oil hydraulic chamber (not shown) so that the lag oil hydraulic chamber and the plunger oil passage 21 communicate with each other. The hydraulic oil is supplied from the plunger 21 to the engagement hole 18a of the holder 18 and the plunger 19 is then thrust against the urging force of the spring 20. As a result of this, the engagement shaft portion 19a of the plunger 19 is pulled out of the engagement hole 18a of the holder 18 so that the plunger 19 and the rotor 7 become disengaged.
Subsequently, the hydraulic oil is supplied by the OCV 27 to the advance oil hydraulic chamber (not shown) via the second pipeline 35 and the second oil passage 26 so as to advance the rotor 7. The oil pressure is transmitted to the plunger oil passage 21 SO as to displace the plunger 19 toward the housing 5 against the urging force of the spring 20, thus disengaging the plunger 19 and the holder 18. The OCV 27 is operated (opened or closed) in this disengaged state so as to control the quantity of oil supplied to the lag oil hydraulic chamber and the advance oil hydraulic chamber, thus controlling the rotation of the rotor 7 with respect to the housing 5. The pressure of the oil supplied via the OCV 27 is subject to feedback control and computation by the ECU 40, in accordance with signals from a position sensor (not shown) for detecting a relative angle of rotation of the rotor 7 with respect to the housing 5 and a crank angle sensor (not shown) for determining the oil pressure applied by the oil pump 37.
In the related-art oil hydraulic actuator described above, when the valve housing 28 of the OCV 27 is introduced into the engine block 39 for installation, the open ends of the pipelines 32-35, provided in the engine block 39 so as to face the respective ports formed in the valve housing 28, may be displaced with respect to the respective ports, in a circumferential or axial direction of the valve housing 28. This results in communication between the pipelines 32-35 and the respective ports being obstructed so that the quantity of flow of the hydraulic oil is reduced.
Accordingly, an object of the present invention is to provide an OCV in which the drawback of the related art is eliminated.
Another and more specific object of the invention is to obtain an OCV provided with a valve housing capable of preventing reduction in the quantity of flow of the hydraulic oil even when the ports are displaced in position with respect to the pipelines.
The aforementioned objects can be achieved by an oil control valve for controlling supply of hydraulic oil to an oil hydraulic actuator via a plurality of pipelines, comprising: a cylindrical housing; a plurality of ports formed in a periphery of said housing so as to correspond to the plurality of pipelines; and grooves provided in the periphery of said housing so as to provide communication between an associated port and an associated pipeline. With this, even when displacement occurs between the pipeline and the port of the valve housing, the grooves ensure communication between the pipeline and the port. Thereby, reduction in the quantity of hydraulic oil is prevented.
The groove may be formed to extend from a bottom of the port to cover an entirety of the periphery of said housing. With this, even when displacement, in a circumferential direction of the valve housing, occurs between the pipeline and the port of the valve housing, the groove ensures communication between the pipeline and the port so that reduction in the quantity of hydraulic oil is prevented.
The groove, formed around the entirety of the valve housing, may have a width smaller than that of the port. With this, even when displacement between the pipeline and the port of the valve housing occurs, communication between the pipeline and the port is ensured so that reduction in the quantity of hydraulic oil is prevented.
The groove, formed around the entirety of the valve housing, may have a width identical to that of the port. With this, even when displacement, in a circumferential direction of the valve housing, occurs between the pipeline and the port of the valve housing, any portion of the groove, provided around the entirety of the valve housing, is available to replace the port for supply of the hydraulic oil. Accordingly, reduction in the quantity of hydraulic oil is successfully prevented.
The groove, formed around the entirety of the valve housing, may have a width larger than that of the port. With this, any portion of the groove, provided around the entirety of the valve housing, is available to replace the port for supply of the hydraulic oil. Accordingly, reduction in the quantity of hydraulic oil is successfully prevented.
The groove may extend from an edge of the port in an axial direction of said housing. With this, even when displacement, in an axial direction of the valve housing, occurs between the pipeline and the port of the valve housing, communication between the pipeline and the port is ensured so that reduction in the quantity of the hydraulic oil is prevented.
The groove, extending from an edge of the port in an axial direction of said housing, may include a taper inclined from the periphery of said housing toward a surface of the port. With this, even when displacement, in an axial direction of the valve housing, occurs between the pipeline and the port of the valve housing, the taper ensures communication between the pipeline and the port so that reduction in the quantity of the hydraulic oil is prevented.